Many internal combustion engine oil pumps are of the gear pump type wherein the drive gear is connected to the engine camshaft, or other rotational power source. The drive gear, in turn, rotates an idler gear, and the pump consists of a main body and cover housing, which are affixed to one another during use. Other engine oil pumps use a rotary gear set having a rotor gear and a stator ring gear. The cover housing may also include a relief valve. An oil inlet or “pick-up tube” is often mounted on the cover housing and is located within the engine pan sump, permitting oil to be drawn into the pump from the crank case.
In high performance engines such as those used in race cars, the high engine RPM causes rapid wear in the oil pump, as such pumps are built to close tolerances in order to achieve the high oil flow necessary to lubricate the rapidly rotating engine. Conventional internal combustion engine oil pumps utilize a drive shaft, driven from the engine camshaft or ignition distributor, and a driven gear is mounted upon the lower end of the drive shaft.